Do ecotypes of bushbuck differ in grouping patterns?

Abstract

Grouping patterns within the genus Tragelaphus suggest that species inhabiting open areas tend to live in larger groups, while species preferring dense habitats live solitarily or in small family groups. We asked if similar variation would be concealed in the within-species variation of bushbuck (Tragelaphus scriptus). Recent molecular phylogeographic analyses revealed several locally adapted forms of bushbuck in different ecoregions on the African continent. We compared group sizes of south-eastern bushbuck (Tragelaphus sylvaticus) among six different populations ("ecotypes"). To date, most data on the social organization of bushbuck have been collected from only one population in Queen Elizabeth National Park (QENP) in Uganda. This particular population, however, inhabits an unusual-comparatively open-habitat type, while bushbuck otherwise inhabit dense habitats, leaving doubt whether data collected in QENP are representative of the entire species. We, therefore, compared grouping patterns between ecotypes inhabiting rather open habitats (e.g., dianae and haywoodi) and ecotypes occupying rather dense habitats (e.g., massaicus and ornatus). In bachelor groups and in all-female (spinster) groups, single sightings were the most frequent "group type" in all populations examined. We detected no significant difference among ecotypes in relative frequencies of group size categories in the case of bachelor groups. Spinster group sizes were slightly (albeit significantly) smaller in QENP than in all other areas. Moreover, a comparison of two areas inside (low human pursuit) and outside Lake Mburo National Park (high hunting pressure) in Uganda revealed no significant difference in grouping patterns in response to human pursuit (as reported for impala [Aepyceros melampus] inhabiting the same area). Altogether, our results suggest that group sizes in bushbuck are not dependent on the habitat type they inhabit; neither does human nuisance have an impact on grouping patterns. Hence, an "almost solitary" lifestyle appears to be a characteristic of the entire taxon.

Population status, feeding ecology and activity pattern of common bushbuck (Tragelaphus Scriptus decula) in Sekele Mariam Forest, West Gojjam, Ethiopia

“…Based on the result, the aggregation of group of bushbuck population in the dry season in a limited area and splitting into smaller groups and dispersal to a wider area may be due to their selective feeding behavior to get more preferable forage and they are mostly solitary. This supports the findings of Wronski et al (2009), which observed that bushbucks are indeed a solitary species, as one individual peer group was the most frequent group size in both adults and sub adult groups in all populations they examined. During the wet season, the solar radiation is reduced by the cloud cover; hence, the animals leave dense forest and congregate in the open for feeding.…”

Ontogenetic changes in the histological features of zonal bone tissue of ruminants: A quantitative approach

“…Our study shows that among our ruminant sample, deer species and some bovid species such as the blue duiker (P. monticola), addax (Addax nasomaculatus) and most of tragelaphine antelopes (Tragelaphus imberbis, T. scriptus, T. spekii, T. strepsiceros), display a relatively long growth period (relative to their size). These species, except for addax and the insular Svalbard reindeer, dwell in wooded and closed habitats, which are environments characterized by lower predation pressure than open habitats (Clutton-Brock et al, 1982;Köhler, 1993;Owen-Smith, 1993;Wronski et al, 2009). Addax dwells in desert, habitat characterized by resource limitation and scarcity of predators (Mallon and Kingswood, 2001 also characterize the habitat of the arctic reindeer from Svalbard archipelago (Aanes et al, 2000).…”

Comparing radio-tracking and visual detection methods to quantify group size measures

“…This is not appropriate in studies of group size distribution because that would mean excluding a large proportion (often the majority) of observed individuals, thus greatly falsifying the results. Similar rightskewed frequency distributions characterise herds of many ungulate species (Sinclair 1977;Clutton-Brock 1982;Gueron 1995;Wronski et al 2009;Ramesh et al 2011;Dar et al 2012;Buuveibaatar 2013;Brennan et al 2015;Djaković et al 2015;Semeñiuk 2015), including the subject of our present paper, the Rocky Mountain mule deer (Odocoileus hemiounus hemionus) (Bowyer 2001;Lingle 2003;Mejía Salazar et al 2016).…”